Air spring seats have long been utilized as the driver's seat in trucks and buses. These air spring seats absorb shock and vibratory loads encountered in vehicle operation better than more conventional coil spring support seats. An example of a vehicle air spring seat is disclosed in Dome U.S. Pat. No. 3,298,654, assigned to a predecessor in interest to the assignee of the present invention.
Such air spring seats have been used in vehicles having a compressed air system to provide selective inflation and deflation of the air spring. These air spring seats were normally installed as original equipment in the vehicle as manufactured. To retrofit an air spring seat into a vehicle with system air, special electrical and air system modifications have to be made to the vehicle, if possible, to accomodate the necessary seat connections.
A manual pumping system for a seat employing a fluid spring system has been suggested in the art. Moore U.S. Pat. No. 3,090,647 discloses a vehicle seat employing an air operated hydraulic spring positioned between the seat base and seat frame. The air to operate the hydraulic spring is provided by a manually operated air pump mounted on and to the side of the seat frame. The Moore patent does not teach how the hydraulic spring is lowered or what happens if the air volume in the hydraulic spring is overpressurized. Moreover, the spherical knob handle for the manual air pump in Moore does not control all functions of the pump.